Intensive Care for Hawaiian Forest Birds
The Hawaiian forest is an ecosystem in peril. It has been decimated by introduced animals and plants, habitat destruction and even introduced wildlife diseases. Extinctions are a worrying reality.
The flagship of the Hawaiian forest, and a keystone species as a seed disperser, is the `alala or Hawaiian crow Corvus hawaiiensis. But just like its habitat, the `alala has suffered tremendously – it is generally considered to be extinct in the wild, with no confirmed sightings of wild birds since 2002. Populations of several other forest bird species are either very small or rapidly decreasing.
Unlike many of the other bird species that have become extinct in Hawaii within living memory, the `alala has a captive population as a safety net. The San Diego Zoo has been involved in conserving the `alala since 1993, initially through its collaboration with The Peregrine Fund. At that time, the global population of `alala had dropped to a low-point of approximately 20 birds, including the small flock that had been established in captivity.
Today the San Diego Zoo Institute for Conservation Research manages the Hawaii Endangered Bird Conservation Program (HEBCP) – a unique partnership with the U.S. Fish & Wildlife Service and the Hawaii Division of Forestry and Wildlife. The goal of the HEBCP is to prevent extinction and promote recovery of critically endangered Hawaiian forest birds, with primary focus on the `alala. All but one of the entire population of `alala is maintained at the Keauhou Bird Conservation Center (KBCC) on the Big Island and the Maui Bird Conservation Center (MBCC).
The `alala has proven a challenging species to propagate in captivity, with efforts hindered by a disappointing rate of hatching healthy chicks, due to high levels of embryonic mortality and congenital abnormalities. Consequently, the `alala is intensively managed using the techniques of behavioral analysis, artificial incubation and hand-rearing, in order to maximize reproductive success.
We are happy to announce that the 2010 breeding season has been the HEBCP’s most productive `alala season to date. The team has hatched a total of 13 chicks, with 11 youngsters being successfully raised to independence. Together with the 8 chicks raised in 2009, the `alala population has risen by 30% in two years, bringing the flock to a total of 77 birds. This represents a significant step away from the potential of extinction and equally, it brings us one step closer to our goal of reestablishing a population in the wild.
In October 2010, 12 captive-bred puaiohi were transferred from MBCC to the island of Kauai, for release into the Alakai Wilderness Area. This release cohort brings the total to precisely 200 puaiohi released by the HEBCP over the past 12 years. During this time, the wild population estimate for puaiohi has doubled to approximately 500 birds.
Two species of Hawaiian honeycreeper are also receiving our attention – the palila and the Maui parrotbill. We are currently developing captive breeding and release techniques, aiming to build the reproductive output of both flocks, with the eventual goal of reintroducing new populations into restored forest habitat. Post-release survival from our trial releases of palila on the northern slopes of Mauna Kea has certainly given us reason for hope.